The present invention relates to an infra-red (IR) receiver having particular, but not exclusive, applications in the transmission of audio on an IR carrier and in remote control applications for audio equipment.
Technical publication 167 by Philips Export BV and release on Mar. 22, 1985 discloses low-power remote control IR transmitter and receiver pre-amplifiers. Infra-red radiation is detected by a photodiode and the electrical signal produced is filtered in an inductive-capacitive filter before being applied to a narrow-band IR receiver of a type TDA 3047/3048 which operates at five volts.
There is now a demand for an infra-red receiver circuit which is so compact that it can be fabricated by integration and which can be operated at about one volt from a single cell battery.
This known circuit can not fulfil these requirements because it is designed to be operated at 5 volts to be compatible with other circuitry, such as a micro-processor, which is included in the control circuit. Additionally an L-C filter cannot per se be integrated because of the coil. A filter is necessary to eliminate interference from sources of light such as incandescent lamps and ambient sunlight. Finally in this known circuit the infra-red diode (or photodiode) is used in a reverse mode in which it dissipates energy from the power supply. In the case of the IR receiver being built-into a mains powered T.V. receiver such a dissipation can be tolerated. However this dissipation is undesirable when using a single cell because under bright light conditions the drain can be as high as 1 mA.